Morphological and Morphometric study of Jugular Foramen in human dry skull of Eastern Indian origin: An Anatomical Investigation

Pratima Baisakh¹*, Lopamudra Nayak², Sujita Pradhan², Saurjya Ranjan Das¹, Sitansu Kumar Panda³

¹Associate Professor, Department of Anatomy, IMS and SUM Hospital, Siksha ‘O’ Anusandhan

(Deemed to be University), Bhubaneswar, India.

²Assistance Professor, Department of Anatomy, IMS and SUM Hospital, Siksha ‘O’ Anusandhan

(Deemed to be University), Bhubaneswar, India.

³Professor, Department of Anatomy, IMS and SUM Hospital, Siksha ‘O’ Anusandhan

(Deemed to be University), Bhubaneswar, India.

*Corresponding Author E-mail: drpbaisakh@gmail.com

ABSTRACT:

Background: Jugular foramen (JF) is one of the complex foramen present in base of skull. It varies in shape and size from side to side in same cranium, in different cranium and in different races. It is associated with many diseases of posterior cranial fossa and many skull base surgeries are being carried out by drilling the skull bone around JF for better exposure. Aim and objectives: The present study aims to carry out the morphological and morphometric analysis of jugular foramen of skulls of eastern Indian origin. Materials and Methods: The study was carried out on 100 JF of 50 dried human skulls. Anteroposterior(width), medio-lateral diameter(length) of JF, width and depth of the jugular fossa were measured. Mean and standard deviation of different measurements of left and right side were statistically analysed by student’s t-test. Presence of dome and septum were also studied. Results: The mean of all the measurements are more on right side than left side but it is statistically insignificant (p>0.05). Bony septum was found in 76% cases on left side and 60% on right side. Complete septation wasn’t found in our study. Domed roof was present in 66% cases on right side as compared to 52% on left side. Conclusion: Shape and size of JF may vary due to different size of internal jugular vein and it’s superior bulb. These variations can be due to constitutional, racial or genetic. This anatomical knowledge of JF may help the neurosurgeons, ENT surgeons and radiologists during their clinical exploration.

KEYWORDS: Jugular foramen, Internal jugular vein, Dome, Septum.

INTRODUCTION:

Jugular foramen is one of the fascinating foramen in the base of skull formed by jugular notch of occipital bone with jugular fossa of petrous part of temporal bone. It communicates posterior cranial fossa with upper part of neck through one third of cranial nerves and main venous channels of brain¹. It is divided by a intrajugular process present along the upper border of foramen into two parts.

The large postero-lateral sigmoid part, which contain sigmoid sinus and meningeal branch of occipital artery, a small antero-medial petrosal part which transmits inferior petrosal sinus and meningeal branch of ascending pharyngeal artery. The cranial nerves 9^th, 10^th and 11^th passes in between these two parts medial to intrajugular process². This foramen is also associated with many diseases of posterior cranial fossa like tumours and inflammatory lesions, that can spread and affect ear. The tumours like schwannoma, glomus jugularae, meningeoma and chordomas affect JF and causes multiple cranial nerve palsies (jugular foramen syndrome)^3,4,5. Many skull base surgeries are being carried out drilling the skull bone around jugular foramen like retrosigmoid approach, transjugular craniotomy which requires petrosectomy to treat above mentioned diseases⁶. So this foramen is a matter of concern to neurosurgeons, ENT surgeons and radiologists. The size, shape, height and volume of jugular foramen varies from person to person and among different races and sexes⁷. The detailed anatomy of JF already studied by many authors from north and south Indian populations. The present study is carried out on dry skulls of eastern Indian origin collected from the college museum.

MATERIAL AND METHODS:

The present study was conducted on100 jugular foramen from 50 dry human skulls of unknown age and sex of eastern Indian origin, collected from the college museum. The study was approved by institutional ethical committee. The following parameters of JF of left (Lt) and right (Rt) side were studied in detail. The measurements were taken by using digital vernier calliper.

Antero-posterior diameter (AP) (width):

Maximum anteroposterior diameter of the foramen

Medio-lateral diameter (length): Maximum medio-lateral diameter of foramen

Septations present in JF: Bony bridges dividing the canal

Presence of dome in JF: Presence or absence of domed bony roof

Width of jugular fossa (WJF): Maximum width of jugular fossa

Depth of jugular fossa (DJF): If domed roof is present then depth is measured from the summit to inferior margin of jugular fossa

Statistical analysis was done by using SPSS and comparison was done between left and right side by student’s t- test.

RESULTS:

Antero-posterior diameter (width):

The range of AP diameter varies from 6.3mm-11.6mm on right side and 5.6mm- 9.5mm on left side and the mean being 9.35mm and 7.63mm on right and left side respectively.

Medio-lateral diameter (length):

The mediolateral diameter ranges from 12.5mm to 21.3mm on right side and 11.3 to 15.6mm on left and the means are 14.17mm and 13.22mm on right and left side respectively.

Width of jugular fossa:

The width of the fossa ranges from 7.6mm to 11.5mm on left side and 8.4mm to 14.7mm on right side and the mean are 10.74mm and 8.81mm on right and left side respectively.

Depth of jugular fossa:

The depth of jugular fossa ranges from 9.3mm to 15.5mm and 8.7mm to 13.8mm on right and left side respectively.

The measurements of different parameters were given in Table 1. Mean of all the parameters found more in right side than left (Figure 1, 2 and 3). But there was no statistical significance found in the different morphometric parameters of both sides of jugular foramen (p>0.05). Length and width of jugular foramen in 84% of skulls are more on right side and 16% skulls more on left side. Bony septum was found in 76% cases on left side and 60% on right side (Table 2, Figure 5). We don’t find complete septum dividing the foramen into compartments and only in one foramen separate opening for inferior petrosal sinus was found. Domed roof is present in 66% cases on right side as compared to 52% on left side. Bilateral domed roof is found in 32% of skulls (Table 2, Figure 4). Results of present study has been compared with other studies which is represented in (Table 3).

Tables and Figures:

Table 1: Dimensions of Jugular Foramen and Jugular Fossa of both sides.

Jugular foramen	Number	Width (mm) Mean±SD	Length (mm) Mean±SD	(WJF) (mm) mean±SD	DJF (mm) mean ±SD
Left side	50	7.63±0.15	13.22±0.15	8.81±0.13	11.52±0.32
Right side	50	9.35±0.21	14.17±0.22	10.74±0.16	12.62±0.42
Student’s t test		P=0.15 NS	P=0.42 NS	P=0.51NS	P=0.95 NS

NS-Not significant, Significant

Table 2: Presence of Septum and Dome in Jugular Foramen.

Jugular foramen	Number	Presence of septum	%	Presence of dome	%
Left	50	38	76	26	52
Right	50	30	60	33	66

Table 3: Comparison with similar studies

Parameters

Rt/Lt

Present study East Indians (mean)

Gupta et al (2014) South Indians (mean)

Das et al (2016)

(mean)

Singh et al (2011) North Indians (mean)

AP (mm)

9.35±0.21

7.63±0.15

11.22±2.47

9.52±1.55

9.37±2.61

6.88±1.72

9.32±2.04

7.34±2.04

ML (mm)

14.17±0.22

13.22±0.15

16.52±2.03

16.02±2.2

13.72±2.7

13.07±2.09

15.67±2.28

14.85±2.89

WJF (mm)

10.74±0.16

8.81±0.13

6.38±1.5

5.69±1.6

7.25±1.82

5.88±1.31

8.99±1.92

7.54±2.07

Depth of JF (mm)

12.62±0.42

11.52±0.32

11.75±3.5

11.13±3.54

12.54±2.59

8.72±1.86

11.11±2.96

11.04±3.75

DISCUSSION:

Jugular foramen present in base of skull transmits main venous channels of brain and important nerves to neck. It is very difficult to access surgically due to its deep seated position and presence of many important structures around it. It is related to internal carotid artery anteriorly, vertebral artery posteriorly, facial nerve laterally and hypoglossal nerve medially⁸. Shape and size of jugular foramen varies according to size of internal jugular vein and its superior bulb. Larger size of right side is visible even in embryonic stage at 23mm size embryo may be due to different pattern of development left and right brachiocephalic vein^8,9. Size of internal jugular vein depends on the drainage of superior sagittal sinus into that side of transverse sinus. According to normal anatomy books the superior sagittal sinus drains into right transverse sinus and the straight sinus drains into left transverse sinus². The transverse sinus drains into sigmoid sinus which continues as internal jugular vein. Internal jugular vein at the site of commencement present a dilation called superior bulb to dampen the venous pressure and it is lodged inside a bony roof called dome¹⁰. But there are wide variations in the drainage of venous sinuses in different individuals and in different racial groups, accordingly morphometry of jugular foramen varies.

The mean antero-posterior diameter in the present study was found to be 9.35mm and 7.63mm on right and left side respectively. These findings coincide, the study by Das et al and Singla et al on north Indian population^11,12. Singla et al found statistically significant difference in AP diameter and width of jugular fossa of right and left side. But a study by Gupta et al on south Indian population shows right and left antero-posterior diameter in their study are 11.22mm and 9.52mm respectively, which is more than the present findings¹³. Similarly the mean medio-lateral Diameter in the present study are 14.17mm and 13.22mm on right and left side respectively. According to Das et al and Singla et al the medio-lateral diameter of right and left side are 13.72mm, 13.07mm and 15.7mm, 14.85mm respectively. These findings are close to our findings on eastern Indian origin. But the data of Gupta et al on south Indian population are 16.52mm and 16.02mm on right and left side of jugular foramen. These values are more than the values of present data. Another study by Kotgirwar and Athvale on south Indian population, reported antero-posterior diameter on right and left side are 15.21mm and 13.72mm where as medio-lateral diameter were 9.3mm and 7.16mm on right and left side¹⁴. This shows that the jugular foramens are elongated antero-posteriorly. This difference may be racial and due to genetic variation. The width of jugular fossa was found in the present study as 10.47mm and 8.81mm on right and left side and the depth of them were 12.62mm and 11.52mm respectively. This findings are statistically insignificant on comparing both sides (p>0.05). But the study by Gupta et al and Singla et al demonstrate significant difference on width of jugular fossa of both sides^. Their values are much less than the present study. Presence of dome in jugular foramen is 66% on right side and 52% on left side which is close to a study by Gupta et al on south Indian population. In contrast a study by Khanday et al reports 40% and 29% skulls on right and left side^15.Sturrock and Saheb et al in their study reported 30%, 49% on right side and 6.4%, 36% on left side respectively^16,17. Presence of dome indicates presence of well defined superior bulb of internal jugular vein. No bilateral absence of jugular fossa found in the present study which is same as the study by Das et al. According to present study partial septum was found in 76% on left side and 60% on right side. Complete compartmentalisation wasn’t found in the present study. The study by Gupta et al on south Indian population shows incomplete partition on 56 % on right side and 58% on left side and complete partitioning on 44% on right side and 42% on left side. A study by Das et al shows complete bipartite compartmentalisation on left foramina found in 7% cases and partial compartmentalization in 3.5% on right side and 11.4% on left side^. Vijisha et al reported partial septum on 73.3% on right side and 80% on left side¹⁸, Hatiboglu reported partial septation on 2.6% on right side and 19.6% on left side¹⁹. The present study don’t reveal any significant difference between right and left side jugular foramen morphometry, though the mean of different parameters are more on right side in contrast to other studies. Complete septation wasn’t found and bilateral absence of dome is also not reported in these skulls of eastern Indian origin.

CONCLUSIONS:

The different variations found in morphometry of jugular foramen may be constitutional, racial or genetic. These findings will be a great help to the neurosurgeons, ENT surgeons and radiologists while dealing with pathology of jugular foramen and its surrounding anatomical structures.

CONFLICTS OF INTEREST:

Nil.

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Received on 12.06.2020 Modified on 13.08.2020

Research J. Pharm. and Tech. 2021; 14(7):3829-3832.

DOI: 10.52711/0974-360X.2021.00664